| 2 | ( | 18 | x | + | 9 | ) | + | 4 | ( | - | 8 | x | + | 7 | ) | + | 13 | = | - | 17 |
| 方程左边 = | 2 | × | 18 | x | + | 2 | × | 9 | + | 4 | ( | - | 8 | x | + | 7 | ) | + | 13 |
| = | 36 | x | + | 18 | + | 4 | ( | - | 8 | x | + | 7 | ) | + | 13 |
| = | 36 | x | + | 31 | + | 4 | ( | - | 8 | x | + | 7 | ) |
| = | 36 | x | + | 31 | − | 4 | × | 8 | x | + | 4 | × | 7 |
| = | 36 | x | + | 31 | − | 32 | x | + | 28 |
| = | 4 | x | + | 59 |
| 4 | x | + | 59 | = | - | 17 |
| 4 | x | = | - | 17 | − | 59 |
| 4 | x | = | - | 76 |
| x | = | - | 76 | ÷ | 4 |
| = | - | 76 | × | 1 4 |
| = | - | 19 | × | 1 |
| x | = | - | 19 |